Telegraph system



J. H. BELL.

TELEGRAPH SYSTEM.

APPLICATION FILED NOV. 2|, 1917.

386,679 Patented Aug. 9, 1921.

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STATES JOHN H. BELL, OF SOUTH ORANGE, NEW JERSEY, ASSIGNOR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPGBATION 0.? NEW' YORK.

TELEGRAPH SYSTEM.

Specification of Letters Patent.

Patented Aug. Q, 1921.

Application filed. November 21, 1917. Serial No. 203,082.

To all whom it concern Be it known that 1, JOHN H. BELL, a citizen of the United States, residing at South Orange, in the county of Essex and State of New Jersey, haveinvented certain new and useful Improvements in Telegraph Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telegraph systems, and more particularly to cable or submarine telegraphy.

The principal object of this invention is to provide a system for improving telegraphic transmission through conductors having high electrostatic capacity by the employment of means directed to preventing the phenomenon commonly referred to in submarine telegraph working as a wandering Zero. 7

It is well understood by those familiar with the art that a succession of current impulses of like polarity applied to a submarine cable have a tendency, due to the electrical characteristics of the cable, to merge or run together, and are manifested at the opposite end of the cable in the form of a continuous current wave in which slight ripples therein are the only indications by which the original impulses may be identified. While it is possible manually to translate messages having such distorted appearance when recorded by means of a sensitive receiving apparatus such as the well known siphon recorder, they are, nevertheless, too nearly blended into a single current effect to be applied successfully to the operation of devices for the control of automatic re-- ceiving means, as commonly employed in printing telegraphs. In seeking to apply printing telegraphs to efficient submarine working, itis, therefore, necessary first to remedy this defect in impulses arriving at the receiving end of a cable in order that the received impulses may be more distinct and clearly defined one from another.

The present invention contemplates the use of a transmitting system wherein socalled curbing effects may be applied to a cable during periods intermediate the transmission of successive message impulses. The invention is carried out by means of electroresponsive circuit controlling means com bined with multiplex distributer' means, whereby a more nearly true electrical zero condition is maintained in a cable. Thus the definition of impulses, after they have traversed a cable, is improved.

This invention is illustrated diagrammatically in the accompanying drawing, in which only so much of a telegraphic equipment is shown as will be necessary to a clear understanding of the present system.

In the drawing, Figure 1, there is shown a circuit arrangement of a transmitting system suitable for practising the features of this invention. The drawing, Fig. 2, is a theoretical illustration of the action of various combinations of current impulses in a telegraph line conductor.

In describing this system the reference character A (Fig. 1) indicates an automatic transmitter, preferably of a tape controlled type, B a group of polarized relays and C a group of neutral relays employed in the curbing operation. D indicates a section or arm of a sending distributer shown in developed form, but preferably to be of a suit able rotary type. The present embodiment of the invention has, for convenience, been shown and arranged for handling message transmission on the impulse code basis of different combinations of live impulses of varying polarities for each character or symbol to be selected according to the well known Baudot system. At the transmitter A, five movable members 15 are adapted to be always in contact either with a left hand or a right-hand contact stop respectively associated therewith. The plus and minus signs at the bus conductors to which these contact stops are connected respectively indicate correspondingly poled sources of grounded line current. Conductors 6-10 extend from the contact levers 15 to respective ones of segments 11-15 of the distributer D. Disregarding for the present the relays B and C, it will be apparent that the segments 11-15 will be energized by current polarities, according to various permutations of positions which the transmit ter levers 15 may be caused to assume due to the action of mechanism under the control of a punched tape. A contactor brush 16 is adapted to pass from left to rightin traversing a path over the distributer D and thereby successively to join the segments 1115 with a collector ring 17 A line or cable conductor 18 extends from the ring 17 to a distant station (not shown) and is energized by the impulses imparted thereto by the distributer D.

Referring more particularly to the features of the present invention, it will be noted that the winding of each polar relay 21-25 is connected in derived circuit from each of the conductors 6-1-0 respectively, and that these circuits continue through the left-hand winding on respective ones of the relays 26-30, from which points the circuits continue over-a bus conductor 19 to an earth connection. Second circuits branching from the conductors 6-10 extend through the right-hand winding of each relay respectively in group 26-30, and thereafter terminate on the grounded bus conductor 19. The relation for the latter connections is such that each relay C connects to the next advanced conductor, the relays 26-29 being respectively connected to 1 the conductors 7-10 while the relay 30 is connected to the conductor 6. The oppositely positioned contact stops on each of the relays l3, connect to oppositely poled sources of grounded current (not shown), as indicated by the con ventional plus and minus signs. The armature or contacting lever of each of these relays is adapted to establish either one or the other of the oppositely poled sources of current with the forward contact on a respective one of the relays C. The normal contact of f each relay at C is" connected to a bus conductor 2O which;connects through a resistance unit 31 to earth. The armature or contacting lever of each'relay 26-30 connects respectively to the short, length segments 36-40 interposed between adjacent ones of the segments 11-15. ,The' relays B are of polarized type and each relay will always respond to the position of the associated transmitter lever, to

bias its armature to engage the contact corresponding withthe polarity opposite to that polarity with which the transmitter lever may bein contact. Although. such energization of the relays B always causes their operation, such operating current routed seri-' ally through the left-hand winding of respective ones of the relays G will act cumulatively'only with similarly poled current 'through the right-hand winding of the latter relays to effect their operation, while oppositely poled currents through the two windings of the relays C will neutralize therein-and the relays will accordingly remain unoperated.

The service features of this system provide that bet ween successive message impulses of' opposite polarities the line or cable will be momentarily grounded and between success r sive message' impulses of like polarities a momentary impulse of current of inverse polarity will be impressed on the cable.

Theoperationsof each associated set of grounded bus conductor 19, and as these ourrents act accumulatively in the two windings of this relay, it will therefore be operated to separate its normal contacts and to close its forward contacts. Since the levers 1 and 2 energize the segments '11 and 12 with current of negative polarity, it is necessary, ac-

cording to this system, to energize the intermediate segment 36 with current of positive polarity. The negative current from the conductor 6 energizes the relay 21 to connect the source ofpositively poled current at this relay with the forward contact of the relay 26, and since the latter relay is now op erated this current continues from the armature of the relay 26 to; the curbing segment 36. It will, therefore, be clear that as the brush 16 passes over the segments 11, 36, and

12, currents corresponding with a negative message impulse, a positive curbing impulse anda second negative message impulse, will be imparted to the cable 18. It will be ob? vious, from the foregoing, that if each-transmitter lever 1-5 is inengagement with its source of negative current, as shown, the armature of each polar relay 21-25 will be biased to connect'its' source of positive current with the forward contacts of its asso-' ciated one of the relays 26-30fasshown in the drawing, and since each one of;thelat- 11615161393 8 will be in its operated position 1 each of the curbing segments 36-410 will be energized by positive current. With the equipment in this position, as the brush 1. 16 sweeps through its path,five message impulses of negative polarity'would be'transe mitted to the line 18-,and following eachone' of these impulses a ourbing impulse of posiit ve current wouldalso betransmitted to the In describing the operation by which the line would be momentarily grounded between successive message impulses of opposite polarity, attention will again be directed to the first two groups of the control equipment; Let it nowbe assumed that the'transnutter lever 1 remains on the source of.

negative current, while the contact lever 2 may be assumed aspositionedto connect 1 with the positively poled current source, This position of the transmitter contacts connects negative current to the left-hand winding of the relay 26,- while positive cur- 130,

rent will traverse the right-hand winding of this relay. Such current relation being differential in the relay 26 it is accordingly not operated, in which position a circuit may be traced from the curbing segment 36 by way of the normal contacts of the relay'26, the bus conductor 20 and the resistance unit 31 to earth. In its next regular trip the brush 20 on arriving over the segment 11 connects negative message current to the line 18. When over the segment 36 the line 18 will be grounded; and while the brush 16 is over the segment 12 positive message current will be included with the line 18.

From the foregoing it will be clear that if the transmitter levers 15 are positioned alternately to engage oppositely poled current sources, beginning with negative at lever 1, all of the relays B although energized will be ineffective, due to the difierential current action in the relays C which will render the latter relays inert, thereby including each one of the curbing segments 36-40 with the ground connection. As the brush 16 now sweeps through its path, five alternate negative and positive impulses of message currents will be impressed on the line 18, and following each of these impulses the line 18 will be momentarily grounded.

The purpose of the resistance 31 is to avoid the possibility of disturbing a duplex balance when transmitting over a duplexed line. The resistance 31 may, therefore, be considered to be equal to the resistance of the combined resistance of the line batteries and any protective or other devices which may be included in circuit therewith. A further advantage in the resistance unit 31 is that sparking at the trailer brush of the distributer would be prevented in case the brush had sufficient breadth to overlap both a message and a curbing segment in passin from segment to segment.

eferring to Fig. 2 of the drawing, the straight line 32 represents a theoretical zero current line of a cable, while the shadow line 33 represents current impulses and may be read from left to right as a negative impulse followed by five positive impulses, a

negative impulse, two positive impulses, four negative impulses, two positive impulses and three negative impulses, etc. At E the line 33 represents theoretically a distortion of the impulses due to the high electrostatic effect of the cable. At F the line 33 represents theoretically the application of the curbing effects of the present invention, the intervals of no current corresponding with the moments during which the cable is grounded, while the short impulses of current correspond with intervals of curbing currents.

It may be mentioned that the potential of the sources of current employed in the curbing operations may be of such value that notwithstanding the fact that these impulses are of short duration they will have the desired effect in overcoming residual currents resulting from the signaling impulses. The potential of the curbing currents would ordinarily be proportioned directly to the length of the cable.

What is claimed is:

1. A system of telegraphy in which positive and negative currents are employed, a main line circuit, means for employing said positive and negative currents in signaling over said line, switching means for grounding said line between impulses of opposite polarities only, and switching means acting with said first mentioned switching means for applying current of inverse polarity to said line onlybetween signaling impulses of the same polarity.

2. A telegraph system comprising a line, a source of current, means for preparing circuits for a plurality of message impulses of positive and negative currents in advance of the application thereof to the line, means controlled by current in the circuits prepared by said means for establishing curbing effects on said line, and 'distributer means for alternately applying the message impulses and the curbing effects to said line.

3. In a telegraph system, a line, a source of current, means for transmitting signal impulses of positive and negative currents over said line, a plurality of relays controlled by the signal impulses, a distributer for connecting the signal impulses with the line, and means jointly controlled by said relays and said distributor for establishing curbing effects on said line following each signal impulse.

4. A system of telegraphy in which positive and negative currents are employed, a main line circuit, transmitting means comprising a plurality of contacts, polarized relays controlled by said transmitter contacts, neutral relays controlled by said transmitter contacts, distributer means including intermediate said transmitter contacts and said line, positive and negative current sources selectable by said polar relays, means controlled by said neutral relays for either selecting an earth connection or the current polarity selected by said polarized relays, and means controlled by said distributer for connecting said line with the selections effected by said neutral relays intermediate successive signaling impulses.

5. In a system of telegraphy, a line circuit, a transmitter equipment, a distributer for rendering said transmitter effective with said line circuit, relay means controlled by said transmitter, means controlled by said relays for establishing changes of electrical condition'on associated portions of said distributer, and means controlled by said distributer for rendering the electrical condicuit, a transmitter equipment comprising a plurality'of contact levers, a first plurality of relays each controlled by an associated by said relays and said distributer for es transmitter lever, a second plurality of relays each controlled by two adjacent transmitter levers, a distributer for successively connecting said transmitter levers with said line circuit for transmitting message impulses thereto, and means jointly controlled tablishing changes of electrical condition in said line circuit on cessation of each message impulse. I

' 7. The method of operating-a telegraph line which consists in transmitting signaling characterized bypermutations ofcurrents of positive andnegative polarities, and during such transmission ingrounding the line between successive signaling impulses of opposite polarities'only and in applying an impulse of inverse polarity only between successive impulses oflike polarity. 1 I

8. The method of, operating a telegraph line which consists in transmitting permutationsott signaling impulses of positive and negative polarities, and during such transmission in grounding theline betweensuccessive impulses of opposite polarities" only and in energizing the line withcurrent of inverse polarity onlybetween successive impulses of like polarity.

9. The method of operating a't'elegraph' line which consists in transmitting signals characterized by permutations of currents of positive and negative polarities, and during such transmission in grounding the line between successive impulses of opposite polarities only and in a plying current of inverse polarity only between successive impulses of like polarity. o a

10. A telegraph system comprising a line,

a: source of current, a transmitter, a plurality of relays controlled by said transmitter,

and distributer means for applying to said line messageimpulses ofpositive andnegative currents, and, cooperating with said re-, lays to apply to the end of said lineto which a the transmitter is connected during an in-t terval between succeeding message impulses of like polarity, an impulse of a polarity opposite to the message impulses to bring the line to a condition of neutrality.

- l1- A telegraph system comprising a line, i asourceof current, a transmitter, a plurality.

r JOHN H. BELL. 

